• # question_answer The concentration of ${{K}^{+}}$ ions in the interior (in) and exterior (ex) of a nerve cell are 400 mM and 15 m M respectively. The electrical potential that exists across the membrane is A)  1.425                          B)  - 0.0843           C)  0.0843                        D)  1.366

$K\xrightarrow{\,}\,K_{Ex}^{+}+{{e}^{-}}$ \begin{align} & \,\,\underline{K_{In}^{+}+{{e}^{-}}\xrightarrow{\,}\,K} \\ & \,\,\underline{K_{In}^{+}\xrightarrow{\,}K_{Ex}^{+}} \\ \end{align} $E={{E}^{o}}-\frac{0.0591}{1}\log \,\frac{{{[{{K}^{+}}]}_{Ex}}}{{{[{{K}^{+}}]}_{In}}}$ $=0-0.0591\,\,\log \,\frac{15}{400}=0.0843\,V$